Oil pump

ABSTRACT

An oil pump includes: a pump housing having a rotor accommodation space in an inner portion of the pump housing; a rotor accommodated in the rotor accommodation space; a shaft portion disposed inside the rotor; and a passage which is provided to straddle at least one of the pump housing and the rotor and the shaft portion and which communicates a pump chamber which is formed by the rotor inside the pump housing with an outside of the pump housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. § 119to Japanese Patent Applications 2018-139395 and 2018-216210, filed onJul. 25, 2018 and Nov. 19, 2018, respectively, the entire contents ofwhich are incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an oil pump, in particular, to an oil pumpwhich is provided with a rotor.

BACKGROUND DISCUSSION

In the related art, an oil pump which is provided with a rotor is known(for example, refer to JP 2008-308991A (Reference 1)).

Reference 1 discloses an oil pump which is provided with an inner rotor,an outer rotor, a pump housing, a rotary shaft, and a passage fordischarging bubbles. The inner rotor includes a plurality of externalteeth. The outer rotor includes a plurality of internal teeth which meshwith the external teeth of the inner rotor. The pump housing houses theinner rotor and the outer rotor. The rotary shaft is disposed (inserted)in the inside of the inner rotor, the outer rotor, and the pump housingand is configured to rotate together with the inner rotor.

The passage for discharging the bubbles communicates a pump chamberbetween the internal teeth and the external teeth with an outside of thepump housing. The passage is provided in the pump housing at a positionin the vicinity of the rotary shaft. The passage is configured todischarge the bubbles which are contained in an oil inside the pumpchamber to the outside of the pump housing to remove the bubbles. Theoil has a much greater specific weight than the bubbles (air).Therefore, during the driving of the oil pump, in the pump chamber, theoil is moved to the outside in a radial direction of the rotary shaft bya centrifugal force. As a result, the bubbles are gathered (movedrelatively) on the inside in the radial direction of the rotary shaft(on the rotary shaft side). In other words, the bubbles are gathered onthe passage side.

However, in the oil pump of Reference 1, since the passage fordischarging the bubbles is provided in the pump housing at a position onthe outside in the radial direction of the rotary shaft and the passageis disposed at a position which is distanced from a central axis line ofrotation of the rotary shaft, even when discharging the bubbles whichare gathered on the inside in the radial direction of the rotary shaftvia the passage, there is an inconvenience in that a centrifugal forceacts on the bubbles which are separated from the oil. As a result, thereis a problem in that the bubbles (the bubbles which are contained in theoil) which are separated from the oil may not be efficiently removed.

Thus, a need exists for an oil pump which is not susceptible to thedrawback mentioned above.

SUMMARY

An oil pump according to an aspect of this disclosure includes a pumphousing having a rotor accommodation space in an inner portion of thepump housing, a rotor accommodated in the rotor accommodation space, ashaft portion disposed inside the rotor, and a passage which is providedto straddle at least one of the pump housing and the rotor and the shaftportion and which communicates a pump chamber which is formed by therotor inside the pump housing with an outside of the pump housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of thisdisclosure will become more apparent from the following detaileddescription considered with the reference to the accompanying drawings,wherein:

FIG. 1 is a view of an inscribed gear pump according to a firstembodiment of the disclosure as viewed from an axial direction of ashaft portion;

FIG. 2 is a sectional diagram of the inscribed gear pump according tothe first embodiment of the disclosure as viewed from an axial directionof the shaft portion;

FIG. 3 is a perspective view illustrating the shaft portion and a bodyof the inscribed gear pump according to the first embodiment of thedisclosure;

FIG. 4 is a view illustrating the shaft portion, an inner rotor, and anouter rotor of the inscribed gear pump according to the first embodimentof the disclosure;

FIG. 5 is a sectional diagram taken along a V-V line of FIG. 4;

FIG. 6 is a diagram for explaining, in order, a discharging process (A)to (C) of bubbles by the inscribed gear pump according to the firstembodiment of the disclosure;

FIG. 7 is a view of an inscribed gear pump according to a secondembodiment of the disclosure as viewed from an axial direction of ashaft portion;

(A) in FIG. 8 is a sectional diagram of a state in which an internalpressure of a pressure chamber is low, taken along a VIIIA-VIIIA line,and (B) in FIG. 8 is a sectional diagram of a state in which theinternal pressure of the pressure chamber is low, taken along aVIIIB-VIIIB line;

(A) in FIG. 9 is a sectional diagram of a state in which the internalpressure of the pressure chamber is high, taken along a VIIIA-VIIIAline, and (B) in FIG. 9 is a sectional diagram of a state in which theinternal pressure of the pressure chamber is low, taken along aVIIIB-VIIIB line;

FIG. 10 is a side view illustrating an opening/closing valve of theinscribed gear pump according to the second embodiment of thedisclosure;

FIG. 11 is a sectional diagram which enlarges an opening/closingmechanism of the shaft portion of the inscribed gear pump according tothe second embodiment of the disclosure;

FIG. 12 is a perspective view illustrating the shaft portion and a bodyof the inscribed gear pump according to the second embodiment of thedisclosure;

FIG. 13 is a diagram illustrating a graph for explaining therelationship between a rotation frequency of an engine and a maingallery oil pressure inside the engine;

FIG. 14 is a diagram for explaining, in order, a discharging process (A)to (E) of bubbles by the inscribed gear pump according to the secondembodiment of the disclosure;

FIG. 15 is a view of a vane pump according to a third embodiment of thedisclosure as viewed from an axial direction of a shaft portion;

FIG. 16 is a sectional diagram illustrating the inscribed gear pumpaccording to a fourth embodiment of the disclosure;

FIG. 17 is an exploded perspective view illustrating a fixed shaft ofthe inscribed gear pump according to the fourth embodiment of thedisclosure; and

FIG. 18 is a schematic diagram for explaining restriction of pivoting ofa first member by a second member of the inscribed gear pump of thefourth embodiment of the disclosure.

DETAILED DESCRIPTION

Hereinafter, a description will be given of an embodiment of thedisclosure based on the drawings.

First Embodiment

A description will be given of a configuration of an inscribed gear pump(an oil pump) 100 according to the first embodiment of the disclosure,with reference to FIGS. 1 to 6.

Configuration of Internally Connected Gear Pump

The inscribed gear pump 100 illustrated in FIG. 1 according to the firstembodiment of the disclosure is installed in an automobile (notillustrated) which is provided with an engine. The inscribed gear pump100 is configured to draw an oil (a lubricating oil) inside an oil panand supply (pump) the oil to movable parts (sliding parts) such asaround pistons of the engine or a crankshaft. The inscribed gear pump100 is a trochoid pump.

The inscribed gear pump 100 is provided with a pump housing 1, aninscribed gear rotor 2 containing an inner rotor 21 including aplurality of external teeth 21 a and an outer rotor 22 including aplurality of internal teeth 22 a, a shaft portion 3, and a passage 4.

The inner rotor 21 and the outer rotor 22 are disposed inside the pumphousing 1 in a state in which the shaft portion 3 is inserted throughthe inner rotor 21 and the outer rotor 22. The inner rotor 21 isconfigured to rotate inside the pump housing 1 according to the shaftportion 3. The outer rotor 22 is configured to rotate inside the pumphousing 1 according to the shaft portion 3 via the inner rotor 21.

As illustrated in FIG. 2, in the first embodiment, the passage 4 (theconfiguration including a first passage portion 41 which is describedlater and a second passage portion 42 which is described later) isprovided to span the inner rotor 21 and the shaft portion 3. The passage4 communicates a pump chamber S1 between the internal teeth 22 a (referto FIG. 1) and the external teeth 21 a (refer to FIG. 1) with theoutside of the pump housing 1. The inscribed gear pump 100 is configuredto discharge bubbles K (refer to FIG. 6(A)) contained in the oil insidethe pump chamber S1 to the outside of the pump housing 1 via the passage4. A detailed description will be given later.

Hereinafter, a description will be given of the detailed configurationof the parts of the inscribed gear pump 100.

Configuration of Pump Housing

As illustrated in FIG. 2, the pump housing 1 includes a body 11 and acover 12. The body 11 and the cover 12 are positioned at one side andthe other side of the axial directions of the shaft portion 3,respectively.

Hereinafter, the axial directions of the shaft portion 3 will bereferred to as A directions, and of the A directions, the directionfacing the cover 12 side from the body 11 side will be referred to as anA1 direction and the opposite direction will be referred to as an A2direction.

The body 11 and the cover 12 are assembled in a state in which anabutting surface 11 a and an abutting surface 12 a which extend indirections orthogonal to the A directions abut against each other. Thebody 11 and the cover 12 include through holes 11 b and 12 b,respectively, on the same axis which extends in the A directions. Theshaft portion 3 is inserted through the through holes 11 b and 12 b.

An inner portion of the pump housing 1 includes a rotor accommodationspace S2 which accommodates the inner rotor 21 and the outer rotor 22.In detail, the body 11 includes a recessed portion which is recessed inthe A2 direction from the abutting surface 11 a. The body 11 and thecover 12 form the rotor accommodation space S2 by blocking the recessedportion of the body 11 with the cover 12.

The thickness directions of the rotor accommodation space S2 are the Adirections, and the rotor accommodation space S2 has a circular columnshape corresponding to the external shape of the outer rotor 22. Theinner rotor 21 and the outer rotor 22 have approximately the samethickness in the A directions.

Therefore, the inner rotor 21 and the outer rotor 22 are configured tocause the A2 direction end surfaces thereof to slide on the body 11 andto cause the A1 direction end surfaces to slide on the cover 12. Inother words, the body 11 includes a sliding surface 11 c on a bottomportion of the recessed portion (the A2 direction side of the rotoraccommodation space S2). The cover 12 includes a sliding surface on theA1 direction side of the rotor accommodation space S2. The slidingsurface of the cover 12 is positioned on the same plane as the abuttingsurface 12 a and is a surface which continues from the abutting surface12 a (that is, the sliding surface of the cover 12 and the abuttingsurface 12 a are the same surface).

As illustrated in FIG. 1, a suction port 51 and a discharging port 52are formed in the pump housing 1.

The suction port 51 functions as an introduction path which guides theoil which is sucked into the apparatus to the pump chamber S1. Thedischarging port 52 functions as an outlet path which guides the oilinside the pump chamber S1 to the outside of the apparatus. The suctionport 51 and the discharging port 52 are provided to span the body 11 andthe cover 12 together. The suction port 51 and the discharging port 52are provided together to be adjacent to the pump chamber S1. The suctionport 51 and the discharging port 52 are not directly continuous witheach other and are provided at angular positions in the circumferentialdirection (the rotation direction) of the shaft portion 3 so as not tooverlap each other.

As illustrated in FIG. 3, the suction port 51 and the discharging port52 of the body 11 side are both formed in a recessed shape which is moredepressed to the A2 direction side than the sliding surface 11 c. Thesuction port 51 and the discharging port 52 of the cover 12 side areboth formed in a recessed shape which is more depressed to the A1direction side than the abutting surface 12 a.

As illustrated in FIG. 1, the suction port 51 is connected to the oilpan (not illustrated) which is positioned on the upstream side of thesuction port 51 and is a supply source of the oil. The suction port 51includes an opening 51 a which communicates with the pump chamber S1 ina portion of the suction port 51 at which the pump chamber S1 expands.The opening 51 a functions as an inflow port in which the oil flows intothe pump chamber S1 from inside the suction port 51.

The discharging port 52 is connected to engine parts (not illustrated)which are positioned on the downstream side of the discharging port 52and are the oil supply destination. The discharging port 52 includes anopening 52 a which communicates with the pump chamber S1 in a portion ofthe discharging port 52 at which the pump chamber S1 contracts. Theopening 52 a functions as an outflow port in which the oil flows outfrom the pump chamber S1 into the discharging port 52.

Configuration of Inner Rotor and Outer Rotor

As illustrated in FIG. 1, the external teeth 21 a of the inner rotor 21are disposed on the inside of the outer rotor 22 to mesh, from theinside, with the internal teeth 22 a of the outer rotor 22. The outerrotor 22 is accommodated in the rotor accommodation space S2. The numberof the external teeth 21 a of the inner rotor 21 is one tooth less thanthe number of the internal teeth 22 a of the outer rotor 22.

The inner rotor 21 is configured to be rotated by the shaft portion 3 (arotary shaft 31 which is described later) which is disposed on theinside. The inner rotor 21 (the shaft portion 3) is configured to rotatearound a central axis line of rotation α which is eccentric with respectto the central axis line of rotation of the outer rotor 22.

When the inner rotor 21 is rotated in an arrow R direction, the outerrotor 22 is rotated in the same direction. During the rotation, theexternal teeth 21 a of the inner rotor 21 and the internal teeth 22 a ofthe outer rotor 22 mesh with each other on the side at which thedistance between the inner rotor 21 and the outer rotor 22 is small, andsince the external teeth 21 a are fewer by one tooth than the internalteeth 22 a on the side at which the distance is great, the externalteeth 21 a and the internal teeth 22 a do not mesh with each other and agap (the pump chamber S1) between the external teeth 21 a and theinternal teeth 22 a is formed.

The inner rotor 21 and the outer rotor 22 produce a pump function bycausing the pump chamber S1 to rotationally move in the arrow Rdirection to expand and contract the pump chamber S1. Therefore, as thevolume of the pump chamber S1 expands, the oil flows from the suctionport 51 into the pump chamber S1. As the volume of the pump chamber S1contracts, the oil flows out from the pump chamber S1 to the dischargingport 52.

A bubble introduction portion 21 c is provided in each of the pluralityof (six) tooth bottoms 21 b of the inner rotor 21. The bubbleintroduction portion 21 c has a recessed shape which is depressed to theinside in the radial direction of the shaft portion 3. The passage 4 (anouter passage portion 41 a of the first passage portion 41 which isdescribed later) is connected to the bubble introduction portion 21 cfrom the inside in the radial direction of the shaft portion 3. Thebubble introduction portion 21 c is disposed between the pump chamber S1and the passage 4. The bubble introduction portion 21 c is configured tocollect the bubbles K of the pump chamber S1 and introduce the collectedbubbles K into the passage 4.

Configuration of Shaft Portion

As illustrated in FIG. 2, the shaft portion 3 includes the rotary shaft31 and a fixed shaft 32. The rotary shaft 31 is attached to the pumphousing 1 from the A2 direction side to be capable of rotating.Meanwhile, the fixed shaft 32 is attached in a fixed manner to the pumphousing 1 (the cover 12) from the A1 direction side.

The rotary shaft 31 has a circular column shape, substantially extendingin the A directions. The rotary shaft 31 includes a belt attachingportion 31 a to which a belt B is attached at an end portion in the A2direction. The rotary shaft 31 is configured to rotationally drive theinner rotor 21 by receiving a rotational driving force (torque) from acrankshaft or the like via the belt B and rotationally driving. Therotary shaft 31 is inserted through (fitted into) the inner rotor 21 bypress-fitting and rotates in synchronization with the inner rotor 21.

The rotary shaft 31 includes a positioning surface 31 b which abutsagainst the A2 direction end surface of the inner rotor 21 to positionthe rotary shaft 31 in the A directions. The positioning surface 31 b ispositioned on substantially the same plane as the sliding surface 11 cof the body 11. The positioning surface 31 b is formed by a leveldifference which reduces the size of the inner diameter of the rotaryshaft 31 on the A1 direction side.

The rotary shaft 31 is also inserted through the through hole 12 b suchthat the end portion of the rotary shaft 31 on the A1 direction side isdisposed inside the through hole 12 b of the cover 12. The rotary shaft31 extends from the body 11 side in the A1 direction to a middleposition in the thickness directions (the A directions) of the cover 12.A recessed portion 31 c which is depressed in the A2 direction is formedin the end surface of the rotary shaft 31 on the A1 direction side. Therecessed portion 31 c has a circular column shape in a cross-sectionorthogonal to the A directions. The central axis line of the recessedportion 31 c is positioned on substantially the same axis as the centralaxis line of rotation α of the rotary shaft 31. A bottom portion 31 d ofthe recessed portion 31 c on the A2 direction side is positioned closerto the A2 direction side than the inner rotor 21.

The fixed shaft 32 is disposed inside the rotary shaft 31 excluding aportion of the fixed shaft 32 on the A1 direction side. The fixed shaft32 is provided with an inner passage portion 41 b of the first passageportion 41 (described later) of the passage 4 and the second passageportion 42 (described later) of the passage 4.

The fixed shaft 32 includes a fixed shaft main body 32 a and a fixedshaft attaching portion 32 b.

The fixed shaft main body 32 a has a circular column shape (acylindrical shape) extending in the A directions. The fixed shaft mainbody 32 a is inserted into the recessed portion 31 c of the fixed shaftmain body 32 a (is fitted into the recessed portion 31 c) from the A1direction side. Therefore, the central axis line of the fixed shaft mainbody 32 a is positioned on substantially the same axis as the centralaxis line of rotation α of the rotary shaft 31. The fixed shaft mainbody 32 a extends from the cover 12 side in the A2 direction to aposition in the vicinity of the A2 direction side end surface (thesliding surface 11 c of the body 11) of the inner rotor 21.

As illustrated in FIG. 4, the fixed shaft attaching portion 32 b has aflat plate shape which extends along the outer surface of the A1direction side of the cover 12 (refer to FIG. 1). The fixed shaftattaching portion 32 b includes a pin mounting hole 320 a and a boltmounting hole 320 b. A positioning pin for restricting the rotation ofthe fixed shaft 32 with respect to the cover 12 is mounted to the pinmounting hole 320 a and a bolt for fixing the fixed shaft 32 to thecover 12 is mounted to the bolt mounting hole 320 b.

As illustrated in FIG. 2, the fixed shaft attaching portion 32 b isprovided with a protruding portion 323 which protrudes in the A2direction and is fitted into the through hole 12 b of the cover 12.

A lubrication chamber 33 is formed between an end surface of the fixedshaft main body 32 a on the A2 direction side and the bottom portion 31d of the recessed portion 31 c of the rotary shaft 31. The lubricationchamber 33 is adjacent to the inner surface of the recessed portion 31 cof the rotary shaft 31 and the outer surface of the fixed shaft mainbody 32 a which slide against each other during the rotation of therotary shaft 31, and the lubrication chamber 33 is configured to supplythe oil inside the lubrication chamber 33 to the surfaces which slideagainst each other.

A lubrication chamber 34 is formed between the end surface of the rotaryshaft 31 on the A1 direction side and the protruding portion 323 of thefixed shaft 32. The lubrication chamber 34 is adjacent to the outersurface of the rotary shaft 31 and the inner surface of the through hole12 b of the cover 12 which slide against each other during the rotationof the rotary shaft 31, and the lubrication chamber 34 is configured tosupply the oil inside the lubrication chamber 34 to the surfaces whichslide against each other.

Configuration of Passage

The passage 4 is provided to span the inner rotor 21 and the shaftportion 3 as described above. The passage 4 includes the first passageportion 41 and the second passage portion 42.

As illustrated in FIG. 5, the first passage portion 41 extends indirections which intersect (directions which are orthogonal to) theaxial directions (the A directions) of the shaft portion 3. FIG. 5illustrates a cross-section which is orthogonal to the A directions at amiddle position of the inner rotor 21 in the A directions. In detail,the first passage portion 41 extends in the radial direction of theshaft portion 3. The first passage portion 41 is disposed at a middleposition of the inner rotor 21 in the thickness directions. The firstpassage portion 41 includes a plurality of (six) outer passage portion41 a and the single inner passage portion 41 b.

The outer passage portion 41 a is formed by a through hole which isprovided in the inner rotor 21. The outer passage portion 41 a isdisposed closer to the outside than the inner passage portion 41 b inthe radial direction of the shaft portion 3. The outer passage portion41 a is provided to span the inner rotor 21 and the rotary shaft 31.Therefore, the outer passage portion 41 a rotates in synchronizationwith the inner rotor 21 and the rotary shaft 31.

One end on the outside of the outer passage portion 41 a is connected tothe tooth bottoms 21 b (the pump chamber S1) of the inner rotor 21 viathe bubble introduction portion 21 c. The other end on the inside of theouter passage portion 41 a is connected to the recessed portion 31 c ofthe rotary shaft 31. Therefore, the outer passage portion 41 acommunicates the pump chamber S1 with the inside of the recessed portion31 c of the rotary shaft 31.

The plurality of outer passage portions 41 a are disposed at the sameposition from each other in the A directions. The plurality of outerpassage portions 41 a are disposed at an equal angular interval in thecircumferential direction (the rotation direction) of the shaft portion3. The plurality of outer passage portions 41 a extend both linearly andradially in the radial direction of the shaft portion 3.

The inner passage portion 41 b is formed using a through hole which isprovided in the fixed shaft 32. Therefore, even if the inner rotor 21and the shaft portion 3 rotate, the inner passage portion 41 b does notrotate. One end on the outside of the inner passage portion 41 b isconnected to the outside surface of the fixed shaft 32. The other end onthe inside of the inner passage portion 41 b is connected to the secondpassage portion 42 on the inside of the fixed shaft 32. The innerpassage portion 41 b has a smaller diameter (the diameter in across-section orthogonal to the directions in which the inner passageportion 41 b extends) than the outer passage portion 41 a.

The inner passage portion 41 b extends linearly in the radial directionof the shaft portion 3. The inner passage portion 41 b is disposed at aposition (refer to FIG. 2) corresponding to the outer passage portion 41a in the A directions so as to communicate with the outer passageportion 41 a at a predetermined rotational position of the rotary shaft31 during the rotation of the inner rotor 21 and the rotary shaft 31(during the rotation of the outer passage portion 41 a).

As illustrated in FIG. 1, the inner passage portion 41 b faces thedischarging port 52 side more than the suction port 51 side. In detail,the inner passage portion 41 b is disposed closer to the dischargingport 52 side than a middle position (the dot-dash line of FIG. 1)between the end portion of the suction port 51 (the opening 51 a) andthe end portion of the discharging port 52 (the opening 52 a) on theside at which the distance between the inner rotor 21 and the outerrotor 22 increases. In other words, the inner passage portion 41 b isconfigured to communicate with the pump chamber S1 via the outer passageportion 41 a at a later point than the timing at which the volume of thepump chamber S1 reaches the maximum. The discharging port 52 (theopening 52 a) is also configured to communicate with the pump chamber S1at a later point than the timing at which the volume of the pump chamberS1 reaches the maximum.

The second passage portion 42 is formed using a through hole which isprovided in the fixed shaft 32 of the shaft portion 3. The secondpassage portion 42 extends in the axial directions (the A directions)along the central axis line of rotation α of the rotary shaft 31 of theshaft portion 3. The central axis line of the second passage portion 42is positioned on substantially the same axis as the central axis line ofrotation α of the rotary shaft 31.

One end of the second passage portion 42 on the A1 direction side isconnected to the outer surface (the outside) of the pump housing 1. Inother words, one end of the second passage portion 42 on the A1direction side is connected to the atmosphere. The other end of thesecond passage portion 42 on the A2 direction side is connected to thelubrication chamber 33. The second passage portion 42 is provided with alateral hole 42 a which is connected to the lubrication chamber 34 andextends in a direction which intersects the A directions. Therefore, thepassage 4 is configured to supply the oil which flows out in tinyamounts from the pump chamber S1 to the lubrication chamber 33 and thelubrication chamber 34 during the discharging of the bubbles K.

Discharging Operation of Bubbles

Next a description will be given of the discharging operation of thebubbles K from the pump chamber S1 via the passage 4 of the inscribedgear pump 100 with reference to FIG. 6(A) to 6(C).

First, as illustrated in FIG. 6(A), the communication between thesuction port 51 and the pump chamber S1 is shut off in a state in whichthe oil is supplied into the pump chamber S1 via the opening 51 a of thesuction port 51. In this state, the pump chamber S1 does not communicatewith any of the suction port 51, the discharging port 52, and thepassage 4.

When the pump chamber S1 rotates in the arrow R direction from the stateof FIG. 6(A), the pump chamber S1 becomes the maximum volume and assumesthe state of FIG. 6(B) while contracting from the maximum volume. In thestate of FIG. 6(B), the pump chamber S1 communicates with the outside ofthe pump housing 1 via the passage 4. In other words, the first passageportion 41 and the second passage portion 42 communicate with each otherand the passage 4 assumes a state of being capable of discharging thebubbles K.

When the pump chamber S1 rotates in the arrow R direction from the stateof FIG. 6(B), the pump chamber S1 assumes the state of FIG. 6(C). In thestate of FIG. 6(C), the pump chamber S1 and the discharging port 52communicate with each other and the communication between the firstpassage portion 41 and the second passage portion 42 is nullified. Inother words, the inscribed gear pump 100 assumes a state in which it ispossible to discharge, to the engine parts (not illustrated) via thedischarging port 52, the oil in which the discharging of the bubbles Kfrom the pump chamber S1 via the passage 4 is completed and which doesnot substantially contain the bubbles K. Hereinabove, the series ofoperations for discharging the bubbles K from the pump chamber S1 iscompleted.

Effects of First Embodiment

In the first embodiment, it is possible to obtain the following effects.

In the first embodiment, as described above, by providing the passage 4to straddle the shaft portion 3 which is disposed on the inside of theinscribed gear rotor 2 (the inner rotor 21), it is possible to disposethe passage 4 at a closer position to the central axis line of rotationof the inscribed gear rotor 2 (the inner rotor 21) as compared to a casein which the passage 4 is provided in the pump housing 1. In otherwords, since it is possible to ensure that a centrifugal force does notsubstantially act on the bubbles which are separated from the oil by acentrifugal force and gathered on the passage 4 side, it is possible toefficiently discharge the bubbles which are separated from the oil viathe passage 4. As a result, it is possible to efficiently remove thebubbles K contained in the oil via the passage 4.

In the first embodiment, as described above, the passage 4 includes thefirst passage portion 41 which is provided to straddle the inscribedgear rotor 2 (the inner rotor 21) and the shaft portion 3 and extends ina direction intersecting the axial directions of the shaft portion 3,and the second passage portion 42 which is provided in the shaft portion3 and extends in the axial directions. Accordingly, it is possible toeasily move the bubbles K to the shaft portion 3 side using the firstpassage portion 41 and it is possible to easily discharge and remove thebubbles K which are moved to the shaft portion 3 side by the firstpassage portion 41 to the outside of the pump housing 1 using the secondpassage portion 42.

In the first embodiment, as described above, the inscribed gear rotor 2which includes the outer rotor 22 and the inner rotor 21, the outerrotor 22 including the plurality of internal teeth 22 a and the innerrotor 21 including the plurality of external teeth 21 a which engagewith the internal teeth 22 a of the outer rotor 22 is used. Accordingly,it is possible to obtain a great output using a comparatively smallstructure according to the inscribed gear rotor 2.

Second Embodiment

Next, a description will be given of the second embodiment withreference to FIGS. 7 to 14. In the second embodiment, unlike the firstembodiment in which the passage 4 for discharging the bubbles isprovided to straddle only the inner rotor 21 and the shaft portion 3, adescription will be given of an example in which a passage 204 fordischarging the bubbles is provided to straddle a pump housing 201 inaddition to an inner rotor 221 and a shaft portion 203. In the secondembodiment, a description will be given of an example in which the shaftportion 203 includes an opening/closing mechanism 6 of the passage 204in addition to the configuration of the first embodiment. In thefigures, configurations that are the same as those of the firstembodiment are depicted with the same reference numerals as in the firstembodiment.

As illustrated in FIG. 7, an inscribed gear pump (an oil pump) 200 inthe second embodiment of the disclosure includes the pump housing 201,an inscribed gear rotor (the rotor) 202, the shaft portion 203, and thepassage 204. The inscribed gear rotor 202 contains the inner rotor 221which includes the plurality of external teeth 21 a, and the outer rotor22 which includes the plurality of internal teeth 22 a.

Configuration of Pump Housing

As illustrated in (A) and (B) in FIG. 8, the pump housing 201 includes abody 211 and the cover 12. (A) and (B) in FIG. 8 illustrate differentstates of the pump housing 201 from those of (A) and (B) in FIG. 9. Indetail, (A) and (B) in FIG. 8 illustrate a state in which the passage204 is closed by the opening/closing mechanism 6 (described later), and(A) and (B) in FIG. 9 illustrate a state in which the passage 204 isopened by the opening/closing mechanism 6.

The body 211 includes a pressure passage 211 a which supplies the oil toa pressure chamber 62 which is provided on the inside of a rotary shaft231 (described later) from the discharging port 52. In other words, thedischarging port 52 and the pressure chamber 62 communicate with eachother via the pressure passage 211 a. Therefore, the rotation frequency(the rotation speed) of the rotary shaft 231 (described later) of theshaft portion 203 increases due to an increase in the rotation frequencyof the engine and the internal pressure of the pressure chamber 62 alsoincreases due to an increase in the internal pressure of the dischargingport 52.

Configuration of Inner Rotor

As illustrated in FIG. 7, the bubble introduction portion 21 c and thethrough hole (the inner passage portion 41 b) are not provided in theinner rotor 221 as they are in the first embodiment. The inner rotor 221is provided with a groove-shaped rotor-side passage portion 241 b whichforms a portion of the passage 204 (a first passage portion 241 which isdescribed later). A detailed description will be given later.

Configuration of Shaft Portion

As illustrated in (A) and (B) in FIG. 8, the shaft portion 203 includesthe rotary shaft 231, the opening/closing mechanism 6 which is providedon the rotary shaft 231 and opens and closes the passage 204, and a plug232 which is provided on the rotary shaft 231.

A recessed portion 231 a which is depressed in the A2 direction isformed in the end surface of the rotary shaft 231 on the A1 directionside. The recessed portion 231 a has a circular column shape in across-section orthogonal to the A directions. The central axis line ofthe recessed portion 231 a is positioned on substantially the same axisas the central axis line of rotation α of the rotary shaft 231. A bottomportion of the recessed portion 231 a on the A2 direction side ispositioned closer to the A2 direction side than the inner rotor 221 (thesliding surface 11 c of the body 211).

Configuration of Open-Close Mechanism of Shaft Portion

As illustrated in (A) and (B) in FIG. 8, the opening/closing mechanism 6is disposed inside the recessed portion 231 a. The opening/closingmechanism 6 includes an opening/closing valve 61, the pressure chamber62, a restriction portion 63, and a compressed coil spring (a biasingmember) 64.

The opening/closing valve 61 has a hollow shape in which the A1direction side is open. The opening/closing valve 61 has a substantiallycircular column outside shape. In a state in which the opening/closingvalve 61 is disposed inside the recessed portion 231 a, theopening/closing valve 61 partitions the inside space of the recessedportion 231 a into two spaces, a space (the pressure chamber 62) on theA2 direction side of the opening/closing valve 61 and a space (a secondpassage portion 242 which is described later) on the A1 direction sideof the opening/closing valve 61. The opening/closing valve 61 performsthe partitioning of the two spaces such that there is no (substantiallyno) exchanging of the oil between the two spaces.

The opening/closing valve 61 is configured to be capable of moving inthe axial directions (the A directions) of the rotary shaft 231. Indetail, the opening/closing valve 61 is configured to be capable ofreciprocal movement in a predetermined area in the A directions withinthe rotary shaft 231 according to the internal pressure of the pressurechamber 62 (the discharging port 52).

The pressure chamber 62 is provided adjacent to the rotary shaft 231 ofthe opening/closing valve 61 on one side (the A2 direction side) of theaxial directions of the rotary shaft 231. As described above, thepressure chamber 62 communicates with the discharging port 52 via thepressure passage 211 a of the body 211. The pressure chamber 62 isconfigured to pressurize the opening/closing valve 61 in the A1direction in accordance with a fluctuation in the internal pressure ofthe pressure chamber 62 to move the opening/closing valve 61 in the A1direction against the biasing force of the compressed coil spring 64.The opening/closing valve 61 separates from the restriction portion 63when the opening/closing valve 61 moves in the A1 direction.

As illustrated in (A) in FIG. 8, the rotary shaft 231 is provided with apressure passage 231 b which communicates the pressure chamber 62 withthe pressure passage 211 a of the body 211. The pressure passage 231 bincludes an annular groove which has an annular shape extending alongthe outside surface of the rotary shaft 231 to surround the rotary shaft231, and a through hole which extends from the annular groove to theinside of the shaft portion 203 in the radial directions to communicatewith the pressure chamber 62.

The restriction portion 63 is formed on the inside surface of therecessed portion 231 a. In detail, the restriction portion 63 is formedby a level difference which reduces the size of the inner diameter ofthe recessed portion 231 a on the A2 direction side. The restrictionportion 63 is positioned closer to the A2 direction side than the innerrotor 221 (the sliding surface 11 c of the body 211). The restrictionportion 63 is configured to restrict the movement of the opening/closingvalve 61 to the pressure chamber 62 side by abutting against theopening/closing valve 61. In other words, the opening/closing valve 61does not move further to the A2 direction side than a position at whichthe opening/closing valve 61 abuts against the restriction portion 63.

The compressed coil spring 64 is provided adjacent to the rotary shaft231 of the opening/closing valve 61 on the other side (the A1 directionside) in the axial directions of the rotary shaft 231 and is configuredto bias the opening/closing valve 61 toward the pressure chamber 62 (therestriction portion 63).

The plug 232 supports the A1 direction end portion of the compressedcoil spring 64. The plug 232 is attached to the A2 direction end portionof the recessed portion 231 a of the rotary shaft 231 using fitting(including screwing). The plug 232 has a through hole which penetratesthe plug 232 in the A directions.

As illustrated in FIGS. 10 and 11, the opening/closing valve 61 includesa sealing wall 61 a and a communication bore 61 b.

The sealing wall 61 a is a wall portion which extends along the innersurface of the recessed portion 231 a of the rotary shaft 231. Thesealing wall 61 a has a function of sealing the passage 204 in themiddle so as not to discharge the bubbles to the outside of the pumphousing 201. The sealing wall 61 a is disposed between the first passageportion 241 and the second passage portion 242 and closes the passage204 (ensures that the bubbles may not be discharged) in a state (referto (A) and (B) in FIG. 8) in which the opening/closing valve 61 abutsagainst the restriction portion 63.

The communication bore 61 b is disposed at a position which deviates inan axial direction (the A2 direction) of the rotary shaft 231 withrespect to the sealing wall 61 a. A plurality (four) of thecommunication bores 61 b are provided. The plurality of communicationbores 61 b are disposed at an equal angular interval in thecircumferential direction (the rotation direction) of the shaft portion203. The plurality of communication bores 61 b extend both linearly andradially in the radial direction of the shaft portion 203. Thecommunication bores 61 b have a function of communicating with thepassage 204 in order to discharge the bubbles to the outside of the pumphousing 201. An annular groove which has an annular shape extendingalong the inner surface of the recessed portion 231 a to surround theopening/closing valve 61 is provided in the outside end portion of thecommunication bores 61 b.

The communication bore 61 b is disposed between the first passageportion 241 and the second passage portion 242 and opens the passage 204(ensures that the bubbles may be discharged) in a state (a state inwhich the rotation frequency of the engine increases and the internalpressure of the discharging port 52 and the pressure chamber 62 isincreased) (refer to (A) and (B) in FIG. 9) in which the opening/closingvalve 61 moves in the A2 direction against the biasing force of thecompressed coil spring 64 and the opening/closing valve 61 separatesfrom the restriction portion 63 by a predetermined distance.

Configuration of Passage

As illustrated in FIG. 11, the passage 204 is provided to straddle thebody 211 of the pump housing 201, the inner rotor 21, and the shaftportion 203 as described above. The passage 204 includes the firstpassage portion 241 and the second passage portion 242.

The first passage portion 241 is provided to straddle the body 211, theinner rotor 221, and the shaft portion 203.

The first passage portion 241 includes a body-side passage portion 241 awhich is provided in the body 211, a rotor-side passage portion 241 bwhich is provided in the inner rotor 221, and a shaft portion-side firstpassage portion 241 c and a shaft portion-side second passage portion241 d which are provided in the shaft portion 203.

The rotor-side passage portion 241 b, the shaft portion-side firstpassage portion 241 c, and the shaft portion-side second passage portion241 d rotate in synchronization with the inner rotor 221 and the rotaryshaft 231. Meanwhile, the body-side passage portion 241 a does notrotate in synchronization with the inner rotor 221 and the rotary shaft231. The shaft portion-side second passage portion 241 d, the rotor-sidepassage portion 241 b, the shaft portion-side first passage portion 241c, and the body-side passage portion 241 a are disposed in order fromthe downstream side (the atmosphere side) (the second passage portion242 side) at which the bubbles are discharged.

As illustrated in FIG. 12, the body-side passage portion 241 a isprovided in the sliding surface 11 c of the body 211. The body-sidepassage portion 241 a has a letter L shape as viewed from the Adirections and is formed in a groove shape which is depressed in the A2direction from the sliding surface 11 c. Therefore, the body-sidepassage portion 241 a extends in a direction which intersects (adirection which are orthogonal to) the axial directions (the Adirections) of the shaft portion 203.

As illustrated in FIG. 7, one end on the outside (the outside of theshaft portion 203 in the radial direction) of the body-side passageportion 241 a is disposed at a position (a position in the vicinity ofthe tooth bottoms 21 b) at which the body-side passage portion 241 acommunicates with the space between adjacent external teeth 21 a in thepump chamber S1 when the inner rotor 221 rotates. The other end on theinside (the inside in the radial direction of the shaft portion 203) ofthe body-side passage portion 241 a is connected to the rotor-sidepassage portion 241 b and the shaft portion-side first passage portion241 c. In other words, the body-side passage portion 241 a communicatesthe pump chamber S1 with the rotor-side passage portion 241 b and theshaft portion-side first passage portion 241 c (the shaft portion-sidesecond passage portion 241 d).

As illustrated in FIG. 11, the rotor-side passage portion 241 b isprovided in the A2 direction end portion on the inner peripheral side ofthe inner rotor 221. The rotor-side passage portion 241 b is formed inan annular groove shape which extends to surround the shaft portion 203.

The shaft portion-side first passage portion 241 c is disposedsubstantially adjacent to the rotor-side passage portion 241 b on the A2direction side. The shaft portion-side first passage portion 241 c isformed by a level difference which reduces the size of the outerdiameter of the rotary shaft 231 on the A1 direction side. The shaftportion-side first passage portion 241 c is formed in an annular shapewhich extends to surround the shaft portion 203. The shaft portion-sidefirst passage portion 241 c is disposed substantially at a positioncorresponding to the body-side passage portion 241 a in the Adirections. The shaft portion-side first passage portion 241 c and therotor-side passage portion 241 b form an annular space which surroundsthe opening/closing valve 61.

The shaft portion-side second passage portion 241 d is formed by athrough hole which is provided in the rotary shaft 231 and extends inthe radial direction of the shaft portion 203. A plurality (four) of theshaft portion-side second passage portions 241 d are provided. Theplurality of shaft portion-side second passage portions 241 d aredisposed at an equal angular interval in the circumferential direction(the rotation direction) of the shaft portion 203. The plurality ofshaft portion-side second passage portions 241 d are disposedsubstantially at positions corresponding to the rotor-side passageportion 241 b in the A directions.

The second passage portion 242 is formed to extend in the A directionsby the inner portion space of the opening/closing valve 61, the innerportion space of the recessed portion 231 a, and the through hole of theplug 232 (refer to FIG. 7).

One end of the second passage portion 242 on the A1 direction side isconnected to the outer surface (the outside) of the pump housing 201. Inother words, one end of the second passage portion 242 on the A1direction side is connected to the atmosphere. The vicinity of the otherend of the second passage portion 242 on the A2 direction side isconnected to the first passage portion 241 in a state (a state in whichthe internal pressure of the pressure chamber 62 is high) in which theopening/closing valve 61 is separated from the restriction portion 63.

Operation of Open-Close Mechanism

A description will be given of the operations of the opening/closingmechanism 6 with reference to (A) and (B) in FIG. 8 and (A) and (B) inFIG. 9.

The opening/closing mechanism 6 is configured to open and close thepassage 204 by causing the opening/closing valve 61 to move reciprocallyin the A directions. (A) and (B) in FIG. 8 illustrate a state in whichthe passage 204 is closed (a state in which the opening/closing valve 61moves to the A2 direction side). Meanwhile, (A) and (B) in FIG. 9illustrate a state in which the passage 204 is open (a state in whichthe opening/closing valve 61 moves to the A1 direction side).Hereinafter, a description will be given of the open state and theclosed state of the passage 204, in order.

As illustrated in (A) and (B) in FIG. 8, in a case in which the internalpressure of the discharging port 52 and the pressure chamber 62 is low,the opening/closing mechanism 6 is configured such that the sealing wall61 a is disposed between the first passage portion 241 and the secondpassage portion 242 in a state in which the opening/closing valve 61 andthe restriction portion 63 abut against each other due to the biasingforce of the compressed coil spring 64. Accordingly, the opening/closingmechanism 6 is configured to close the passage 204. A case in which theinternal pressure of the discharging port 52 and the pressure chamber 62is low is a case in which the rotation frequency (the rotational speed)of the rotary shaft 231 is comparatively low.

Meanwhile, as illustrated in (A) and (B) in FIG. 9, in a case in whichthe internal pressure of the discharging port 52 and the pressurechamber 62 is high, the opening/closing mechanism 6 is configured suchthat, instead of the sealing wall 61 a, the communication bore 61 b isdisposed between the first passage portion 241 and the second passageportion 242 in a state in which the opening/closing valve 61 and therestriction portion 63 are separated by a predetermined distance againstthe biasing force of the compressed coil spring 64 via theopening/closing valve 61 due to the internal pressure of the pressurechamber 62. Accordingly, the opening/closing mechanism 6 is configuredto open the passage 204. A case in which the internal pressure of thedischarging port 52 and the pressure chamber 62 is high is a case inwhich the rotation frequency (the rotational speed) of the rotary shaft231 is comparatively high.

For example, as illustrated in FIG. 13, the opening/closing mechanism 6opens the passage 204 using the opening/closing valve 61 in a case inwhich a rotation frequency R per unit time of the engine is greater thanor equal to 4000 rpm and closes the passage 204 using theopening/closing valve 61 in a case in which the rotation frequency R isless than 4000 rpm. Accordingly, the oil pressure of the main galleryinside the engine is reduced in a high-speed rotation region. FIG. 13illustrates a graph of an inscribed gear pump of the related art using adotted line as a comparative example. The inscribed gear pump of therelated art is configured to discharge the bubbles at all enginerotation frequencies regardless of the engine rotation frequency.

Discharging Operation of Bubbles

Next a description will be given of the discharging operation of thebubbles from the pump chamber Si via the passage 204 of the inscribedgear pump 200 with reference to FIGS. 14(A) to 14(E). In each of thestates of FIGS. 14(A) to 14(E), the passage 204 is in an open state (astate in which the communication bore 61 b of the opening/closing valve61 is disposed between the first passage portion 241 and the secondpassage portion 242).

First, as illustrated in FIG. 14(A), the oil is supplied into the pumpchamber S1 from the suction port 51 in a state in which the opening 51 aof the suction port 51 and the pump chamber S1 communicate with eachother.

When the pump chamber S1 rotates in the arrow R direction from the stateof FIG. 14(A), the pump chamber S1 assumes the state of FIG. 14(B) whileexpanding in volume. In the state of FIG. 14(B), the communicationbetween the suction port 51 and the pump chamber S1 is shut off in astate in which the oil is supplied into the pump chamber S1, and thepump chamber S1 reaches the maximum volume. In this state, the pumpchamber S1 does not communicate with any of the suction port 51, thedischarging port 52, and the passage 204.

When the pump chamber S1 rotates in the arrow R direction from the stateof FIG. 14(B), the pump chamber S1 assumes the state of FIG. 14(C) whilecontracting in volume from the maximum volume. In this state, the pumpchamber S1 does not communicate with any of the suction port 51, thedischarging port 52, and the passage 204.

When the pump chamber S1 rotates in the arrow R direction from the stateof FIG. 14(C), the pump chamber S1 assumes the state of FIG. 14(D) whilefurther contracting in volume. In the state of FIG. 14(D), since thepump chamber S1 communicates with the body-side passage portion 241 awhich is shaped like a groove in a character L shape, the pump chamberS1 communicates with the outside of the pump housing 201 via the passage204. In other words, the first passage portion 241 and the secondpassage portion 242 communicate with each other and the bubbles aredischarged via the passage 204.

When the pump chamber S1 rotates in the arrow R direction from the stateof FIG. 14(D), the pump chamber S1 assumes the state of FIG. 14(E) whilefurther contracting in volume. In the state of FIG. 14(E), thecommunication between the pump chamber S1 and the passage 204 isnullified and the pump chamber S1 and the opening 52 a of thedischarging port 52 are communicated with each other. The inscribed gearpump 200 assumes a state in which it is possible to discharge, to theengine parts (not illustrated) via the discharging port 52, the oil inwhich the discharging of the bubbles from the pump chamber S1 via thepassage 204 is substantially completed and which does not substantiallycontain the bubbles. Hereinabove, the series of operations fordischarging the bubbles from the pump chamber S1 is completed.

Effects of Second Embodiment

In the second embodiment, it is possible to obtain the followingeffects.

In the second embodiment, as described above, the shaft portion 203includes the opening/closing mechanism 6 which opens and closes thepassage 204. Accordingly, since it is possible to close the passage 204in a period (at a timing) in which the discharging of the bubbles to theoutside of the pump housing 201 is unnecessary using the opening/closingmechanism 6, it is possible to prevent the oil from flowing out to theoutside of the pump housing 201 together with the bubbles via thepassage 204 in the period in which the discharging of the bubbles isunnecessary. The period in which the discharging of the bubbles isunnecessary is, for example, a period in which the rotation frequency ofthe engine is low and the bubbles are not easily formed in the oil.

In the second embodiment, as described above, the passage 204 includesthe first passage portion 241 which is provided to straddle the pumphousing 201, the inner rotor 221, and the shaft portion 203 and extendsin a direction intersecting the axial directions of the shaft portion203, and the second passage portion 242 which is provided in the shaftportion 203 and extends in the axial directions, the shaft portion 203includes the rotary shaft 231 which rotationally drives the inner rotor221, the rotary shaft 231 includes the opening/closing mechanism 6 whichopens and closes the passage 204, the opening/closing mechanism 6includes the opening/closing valve 61 including the sealing wall 61 aand the communication bore 61 b which is disposed at a position deviatedin an axial direction of the rotary shaft 231 with respect to thesealing wall 61 a and the opening/closing valve 61 is capable of movingin the axial direction of the rotary shaft 231, and the opening/closingmechanism 6 is configured to close the passage 204 by moving in one ofthe axial directions of the rotary shaft 231 to dispose the sealing wall61 a between the first passage portion 241 and the second passageportion 242 and to open the passage 204 by moving in the other axialdirection of the rotary shaft 231 to dispose, instead of the sealingwall 61 a, the communication bore 61 b between the first passage portion241 and the second passage portion 242. Accordingly, since it ispossible to open and close the passage 204 merely by providing thesealing wall 61 a which has a function of blocking the passage 204 andthe communication bore 61 b which has a function of communicating withthe passage 204 in a single member (the opening/closing valve 61) andmoving the single member (the opening/closing valve 61), it is possibleto easily perform the opening and closing of the passage 204 and it ispossible to simplify the configuration of the opening/closing mechanism6.

In the second embodiment, as described above, the opening/closingmechanism 6 is configured to move the opening/closing valve 61 accordingto an internal pressure of the discharging port 52 and is configured toclose the passage 204 by disposing the sealing wall 61a between thefirst passage portion 241 and the second passage portion 242 in a casein which the internal pressure of the discharging port 52 is low and toopen the passage 204 by disposing, instead of the sealing wall 61 a, thecommunication bore 61 b between the first passage portion 241 and thesecond passage portion 242 in a case in which the internal pressure ofthe discharging port 52 is high. Accordingly, in a case in which therotation frequency of the engine is lowered and the internal pressure ofthe discharging port 52 is low to an extent in which the bubbles are noteasily formed in the oil, it is possible to close the passage 204.However, in a case in which the rotation frequency of the engine israised and the internal pressure of the discharging port 52 is high toan extent in which the bubbles are easily formed in the oil, it ispossible to open the passage 204. In other words, it is possible toeffectively remove the bubbles contained in the oil while suppressingthe flowing out of the oil to the outside of the pump housing 201.

In the second embodiment, as described above, the opening/closingmechanism 6 includes the pressure chamber 62 which is provided on oneside in the axial directions of the rotary shaft 231 of theopening/closing valve 61, communicates with the discharging port 52 viathe pressure passage 211 a, and pressurizes the opening/closing valve 61to move the opening/closing valve 61, the compressed coil spring 64which is provided on another side in the axial directions of the rotaryshaft 231 of the opening/closing valve 61 and biases the opening/closingvalve 61 toward the pressure chamber 62, and the restriction portion 63which restricts movement of the opening/closing valve 61 to the pressurechamber 62 side, and the opening/closing mechanism 6 is configured toclose the passage 204 by disposing the sealing wall 61 a between thefirst passage portion 241 and the second passage portion 242 in a statein which the opening/closing valve 61 and the restriction portion 63 arecaused to abut against each other by a biasing force of the compressedcoil spring 64 in a case in which the internal pressure of thedischarging port 52 and the pressure chamber 62 is low and to open thepassage 204 by disposing, instead of the sealing wall 61 a, thecommunication bore 61 b between the first passage portion 241 and thesecond passage portion 242 in a state in which the opening/closing valve61 and the restriction portion 63 are separated against the biasingforce of the compressed coil spring 64 via the opening/closing valve 61by the internal pressure of the pressure chamber 62 in a case in whichan internal pressure of the discharging port 52 and the pressure chamber62 is high. Accordingly, it is possible to configure the opening/closingmechanism 6 from only structural and mechanical configuration elements(the pressure chamber 62, the opening/closing valve 61, the compressedcoil spring 64, and the restriction portion 63) without using electricalconfiguration elements. Therefore, since it is not necessary to providea configuration for supplying electrical power or the like to theopening/closing mechanism 6, it is possible to simplify theconfiguration of the opening/closing mechanism 6.

The other effects of the second embodiment are similar to those of thefirst embodiment.

Third Embodiment

Next, a description will be given of the third embodiment with referenceto FIG. 15. In the third embodiment, instead of the first embodiment inwhich the configuration is provided with the inscribed gear rotor 2, adescription will be given of an example of a configuration which isprovided with a vane rotor 302. In the figures, configurations that arethe same as those of the first embodiment are depicted with the samereference numerals as in the first embodiment.

As illustrated in FIG. 15, a vane pump (the oil pump) 300 in the thirdembodiment of the disclosure is provided with a pump housing 301, a camring 307, the vane rotor 302 containing a rotor main body 321 and aplurality of (eight) vanes 322, the shaft portion 3, and the passage 4.In other words, the third embodiment is provided with the sameconfiguration as the first embodiment in relation to the shaft portion 3and the passage 4.

The pump housing 301 includes a circular cylindrical space on theinside. The annular cam ring 307 is fitted into the inside of the space.

The vane rotor 302 has an annular shape and is disposed inside the camring 307. A gap (a space) is formed between an outer peripheral surfaceof the vane rotor 302 and the inner peripheral surface of the cam ring307.

The shaft portion 3 is inserted through the rotor main body 321. Therotor main body 321 is configured so as to be rotated by the shaftportion 3 inside the pump housing 301.

The vanes 322 are provided to protrude outward from the rotor main body321. The vanes 322 extend in the radial direction of the rotor main body321 (the shaft portion 3). The plurality of vanes 322 are disposed at asubstantially equal angular interval in the circumferential direction ofthe rotor main body 321 (the shaft portion 3). In other words, theplurality of vanes 322 are disposed radially as viewed from the axialdirections of the shaft portion 3 (as viewed from the A directions).

The vanes 322 are attached to the rotor main body 321 to be capable ofproceeding and withdrawing in the radial direction of the rotor mainbody 321 (the shaft portion 3). A back pressure groove (notillustrated), which is a space which is connected to the inside endsurface of the vanes 322, is provided on the inside of the rotor mainbody 321. The back pressure groove is configured such that a backpressure oil is supplied to the back pressure groove to cause (to bias)the vanes 322 to move to the outside in the radial direction of therotor main body 321 (the shaft portion 3). Accordingly, the outside endportion of the vanes 322 maintains a state of being in contact (apressing state) with the inner peripheral surface of the cam ring 307. Apump chamber S301 is formed between the adjacent vanes 322, the innerperipheral surface of the cam ring 307, and the outer peripheral surfaceof the rotor main body 321.

A suction port 351 and a discharging port 352 are formed in the pumphousing 301. The suction port 351 and the discharging port 352 are notdirectly continuous with each other and are provided at angularpositions in the circumferential direction (the rotation direction) ofthe shaft portion 3 so as not to overlap each other.

The vane pump 300 (the vane rotor 302) causes the pump chamber S301 torotate in the arrow R direction around the shaft portion 3 to pump theoil from the suction port 351 to the discharging port 352.

In the third embodiment, the passage 4 is provided to straddle the rotormain body 321 and the shaft portion 3. The portion (the outer passageportion 41 a) of the passage 4 on the rotor main body 321 side isprovided, one between each pair of adjacent vanes 322. The passage 4communicates the pump chamber S301 and the outside of the pump housing301 with each other. The vane pump 300 is configured to discharge thebubbles contained in the oil inside the pump chamber S301 to the outsideof the pump housing 301 via the passage 4.

The other configurations of the third embodiment are similar to those ofthe first embodiment.

Effects of Third Embodiment

In the third embodiment, it is possible to obtain the following effects.

In the third embodiment, as described above, the vane rotor 302 whichincludes the rotor main body 321 and the plurality of vanes 322 whichare provided to protrude outward from the rotor main body 321 and formthe pump chamber S301 is used. Accordingly, it is possible to render thevane pump 300 a simple shape in which foreign matter and the like do noteasily get stuck using the vane rotor 302.

The other effects of the third embodiment are similar to those of thefirst embodiment.

Fourth Embodiment

Next, a description will be given of the fourth embodiment withreference to FIGS. 16 to 18. In the fourth embodiment, a descriptionwill be given of an example of a configuration in which, unlike in thefirst embodiment in which the fixed shaft 32 is configured from a singlemember, the fixed shaft 32 is configured from a plurality of (two)members. In the figures, configurations that are the same as those ofthe first embodiment are depicted with the same reference numerals as inthe first embodiment.

As illustrated in FIG. 16, an inscribed gear pump (the oil pump) 400 inthe fourth embodiment of the disclosure is provided with a shaft portion403.

The shaft portion 403 includes the rotary shaft 31 and a fixed shaft432.

The fixed shaft 432 includes a first member 433 which is fixed to thecover 12 of the pump housing 1 and a second member 434 which is insertedinto the recessed portion 31 c and is connected to the first member 433in a state of being capable of moving in a direction orthogonal to theaxial directions. The second member 434 is disposed (is floatingmounted) in a state of being interposed between the rotary shaft 31 andthe first member 433 without being fixed to the other configurations.

As illustrated in FIG. 17, the fixed shaft 432 includes a turn-stoppingportion 435 which connects the first member 433 and the second member434 to each other in a state in which the second member 434 is capableof moving in a direction orthogonal to the axial directions relative tothe first member 433.

As illustrated in FIG. 16, the second member 434 is substantially rodshaped and extends in the A directions. The second member 434 is formedin a cylindrical shape such that the A2 direction side of the secondmember 434 is inserted into the recessed portion 31 c of the rotaryshaft 31. It is preferable that the distance between the inner surfacewhich extends in the A directions of the recessed portion 31 c and thecylindrical inner surface of the second member 434 be maintained at lessthan or equal to 0.1 mm, for example. Accordingly, it is possible tocontinue forming an oil membrane between the inner surface which extendsin the A directions of the recessed portion 31 c and the cylindricalinner surface of the second member 434 without the sealing propertiesbeing damaged. The second member 434 is positioned by the inner surfaceof the recessed portion 31 c in a direction orthogonal to the Adirections.

The first member 433 is attached to the cover 12 in a fixed manner usinga fixing means such as a bolt (not illustrated). The A2 direction endportion of the first member 433 includes an engagement recessed portion433 a which functions as the turn-stopping portion 435. The A1 directionend portion of the second member 434 includes an engagement protrudingportion 434 a which functions as the turn-stopping portion 435.

The engagement protruding portion 434 a is formed in a substantiallyrectangular shape as viewed from the A1 direction side. In detail, theengagement protruding portion 434 a is formed such that the opposingsides of one pair of sides are linearly parallel to each other as viewedfrom the A1 direction side, and the opposing sides of the other pair ofsides are formed in a curved shape which expands toward the outside.

The engagement recessed portion 433 a is depressed in the A1 directionfrom the A2 direction end portion of the first member 433. Theengagement recessed portion 433 a is formed in a shape (a substantiallyrectangular shape) corresponding to the engagement protruding portion434 a as viewed from the A2 direction side. In detail, the engagementrecessed portion 433 a is formed in a shape substantially correspondingto a shape in which a shape of the engagement protruding portion 434 aas viewed from the A1 direction side is slightly offset to the outside.

Therefore, the engagement protruding portion 434 a is configured to becapable of being inserted into the engagement recessed portion 433 afrom the A2 direction side. The engagement recessed portion 433 a isconfigured to allow the rotation and movement in a direction orthogonalto the A directions of the engagement protruding portion 434 a (thesecond member 434) in a range that does not inhibit the positioning ofthe second member 434 by the inner surface of the recessed portion 31 cand to restrict movement of the second member 434 greater than or equalto a predetermined amount of movement.

The (outside surface of the) engagement protruding portion 434 a isdisposed on the inner surface of the engagement recessed portion 433 ato be separated from (the inner surface of) the engagement recessedportion 433 a by a tiny gap in a direction orthogonal to the Adirections. According to the tiny gap which are orthogonal to the Adirections, the second member 434 is configured to be capable of movingin the direction orthogonal to the A directions with respect to thefirst member 433 which is fixed to the cover 12.

The second member 434 is disposed to be separated from each of thebottom portion 31 d of the recessed portion 31 c of the rotary shaft 31and the first member 433 at both ends in the A directions by a tiny gap(for example, a gap of less than or equal to 0.5 mm on one side) of adegree which allows inclination and movement of the second member 434.

As illustrated in FIG. 18, during the movement of the rotary shaft 31from the stopped state to the driving state, although the second member434 also rotates a little together with the rotation of the rotary shaft31, the rotation of the second member 434 is swiftly restricted due tothe second member 434 abutting against the first member 433 from theinside.

The second passage portion 42 which penetrates the fixed shaft 432 inthe A directions is provided in the fixed shaft 432 (the first member433 and the second member 434). The first passage portion 41 (thelateral hole) which communicates with the second passage portion 42 fromthe outside is provided in the second member 434.

The other configurations of the fourth embodiment are similar to thoseof the first embodiment.

Effects of Fourth Embodiment

In the Fourth embodiment, it is possible to obtain the followingeffects.

In the fourth embodiment, as described above, the shaft portion 403includes the rotary shaft 31 which includes the recessed portion 31 chaving a circular cross-section that is orthogonal to the axialdirections of the shaft portion 403 and extends in the axial directionsand which rotates together with the inscribed gear rotor 2, and thefixed shaft 432 which includes the first member 433 which is fixed tothe pump housing 1 and the second member 434 which is inserted into therecessed portion 31 c and is connected to the first member 433 in astate of being capable of moving in a direction orthogonal to the axialdirections. Accordingly, since it is possible to allow the movement ofthe fixed shaft 432 (the second member 434) in a direction orthogonal tothe axial directions relative to the rotary shaft 31, it is possible tomore uniformly maintain the clearance between the fixed shaft 432 (thesecond member 434) and the recessed portion 31 c in the circumferentialdirection of the fixed shaft 432 (the second member 434) as compared toa case in which the entirety of the fixed shaft is completely fixed tothe pump housing. Accordingly, it is possible to suppress the clearancebetween the fixed shaft 432 and the recessed portion 31 c in thecircumferential direction of the fixed shaft 432 becoming too great andthe sealing properties being inhibited. It is possible to suppress theclearance between the fixed shaft 432 and the recessed portion 31 cbecoming too small and the rotation of the rotary shaft 31 beingprevented by the fixed shaft 432. In a case in which the entirety of thefixed shaft is completely fixed to the pump housing, it is necessary toconsider, during the manufacturing, the tolerance between the rotaryshaft and the fixed shaft and the tolerance between the fixed shaft andthe configurations (the flange and the like) for attaching the fixedshaft to the pump housing. However, in the configuration of the fourthembodiment, it is sufficient to only consider the tolerance between therotary shaft 31 and the first member 433 during the manufacturing. Inother words, it is possible to easily maintain a uniform clearancebetween the fixed shaft 32 (the second member 434) and the engagementrecessed portion 433 a.

In the fourth embodiment, as described above, the fixed shaft includesthe turn-stopping portion 435 (the engagement recessed portion 433 a andthe engagement protruding portion 434 a) which connects the first member433 and the second member 434 to each other in a state in which thesecond member 434 is capable of moving in a direction orthogonal to theaxial directions relative to the first member 433. Accordingly, it ispossible to easily realize a configuration which connects the secondmember 434 and the first member 433 to each other in a state in whichthe movement of the fixed shaft 432 (the second member 434) in adirection orthogonal to the axial directions relative to the rotaryshaft 31 using the turn-stopping portion 435 (the engagement recessedportion 433 a and the engagement protruding portion 434 a).

The other effects of the fourth embodiment are similar to those of thefirst embodiment.

MODIFICATION EXAMPLE

It should be understood that the embodiments disclosed herein have beenpresented for the purpose of illustration and description but notlimited in all aspects. It is intended that the scope of the disclosureis indicated not by the description of the embodiments but by the scopeof the claims and encompasses all modifications (modification examples)equivalent in meaning and scope to the claims.

For example, although an example is depicted in which the biasing memberof the disclosure is configured using a compressed coil spring in thesecond embodiment, the disclosure is not limited thereto. In thedisclosure, the biasing member of the disclosure may be configured usingan elastic member other than a compressed coil spring such as a rubbermember.

Although an example is depicted in which the rotation frequency of theengine is configured to open the opening/closing mechanism in ahigh-speed rotation region greater than or equal to 4000 rpm in thesecond embodiment, the disclosure is not limited thereto. In thedisclosure, the rotation frequency of the engine may be configured toopen the opening/closing mechanism at a predetermined rotation frequencywhich is lower than or greater than or equal to 4000 rpm.

Although an example is depicted in which the passage is provided tostraddle at least the inner rotor in the first and second embodiments,the disclosure is not limited thereto. In the disclosure, the passagemay not be provided to straddle the inner rotor. For example, thepassage may be provided to straddle only the pump housing and the shaftportion.

Although an example (an example in which the opening/closing mechanismis a structural, mechanical configuration) is depicted in which theopening/closing mechanism is configured to open and close using theinternal pressure of the discharging port (the pressure chamber) in thesecond embodiment, the discharging port is not limited thereto. In thedisclosure, for example, the opening/closing mechanism may be configured(may adopt an electrical configuration) to open and close based on anelectrical signal without using the internal pressure of the dischargingport (the pressure chamber).

Although an example is depicted of a configuration in which the passage(the outer passage portion of the first passage portion) is connected toall of the tooth bottoms of the inner rotor in the first embodiment, thedisclosure is not limited thereto. In the disclosure, a configurationmay be adopted in which the passage (the outer passage portion of thefirst passage portion) is connected to the tooth bottoms of a portion ofthe plurality of tooth bottoms of the inner rotor.

Although an example is depicted in which the inner passage portion ofthe first passage portion is configured using a single through hole inthe first embodiment, the disclosure is not limited thereto. In thedisclosure, the inner passage portion of the first passage portion maybe configured using a plurality of through holes.

Although an example is depicted in which the first passage portion isdisposed in a middle position in the thickness directions of the innerrotor in the axial directions of the shaft portion in the firstembodiment, the disclosure is not limited thereto. In the disclosure,the first passage portion may be disposed at a position which isdeviated from the middle position in the thickness directions of theinner rotor. The first passage portion may be disposed at a positionwhich is deviated in the circumferential direction (the rotationdirection) of the shaft portion from that of the first passage portionof the first embodiment.

Although an example is depicted in which the inner passage portion isconfigured using a through hole having a smaller inner diameter than theouter passage portion in the first and third embodiments, the disclosureis not limited thereto. In the disclosure, the inner passage portion maybe configured using a through hole having an inner diameter of a sizegreater than or equal to that of the outer passage portion.

Although an example is depicted in which the passage on the cover sideand the atmosphere communicate with each other in the first to thirdembodiments, the disclosure is not limited thereto. In the disclosure,the passage on the body side and the atmosphere may communicate witheach other.

Although an example is depicted in which the movement of the secondmember in a direction orthogonal to the axial directions with respect tothe first member (a fixed configuration) is rendered possible by aclearance which is provided between the first member and the secondmember in the fourth embodiment, the disclosure is not limited thereto.In the disclosure, for example, the first member and the second membermay be connected to each other using an elastic member such as rubber torender the movement of the second member in a direction orthogonal tothe axial directions with respect to the first member (a fixedconfiguration) possible.

An oil pump according to an aspect of this disclosure includes a pumphousing having a rotor accommodation space in an inner portion of thepump housing, a rotor accommodated in the rotor accommodation space, ashaft portion disposed inside the rotor, and a passage which is providedto straddle at least one of the pump housing and the rotor and the shaftportion and which communicates a pump chamber which is formed by therotor inside the pump housing with an outside of the pump housing.

In the oil pump according to the aspect of this disclosure, as describedabove, by providing the passage to straddle the shaft portion which isdisposed on the inside of the rotor, it is possible to dispose thepassage at a closer position to the central axis line of rotation of therotor as compared to a case in which the passage is provided in the pumphousing. In other words, since it is possible to ensure that acentrifugal force does not substantially act on the bubbles which areseparated from the oil by a centrifugal force and gathered on thepassage side, it is possible to efficiently discharge the bubbles whichare separated from the oil via the passage. As a result, it is possibleto efficiently remove the bubbles contained in the oil via the passage.

In the oil pump according to the aspect, it is preferable that thepassage includes a first passage portion which is provided to straddleat least one of the pump housing and the rotor and the shaft portion andextends in a direction intersecting an axial direction of the shaftportion, and a second passage portion which is provided in the shaftportion and extends in the axial direction.

According to this configuration, it is possible to easily move thebubbles to the shaft portion side using the first passage portion and itis possible to easily discharge and remove the bubbles which are movedto the shaft portion side by the first passage portion to the outside ofthe pump housing using the second passage portion.

In the oil pump according to the aspect, it is preferable that the shaftportion includes an opening/closing mechanism which opens and closes thepassage.

According to this configuration, since it is possible to close thepassage in a period (at a timing) in which the discharging of thebubbles to the outside of the pump housing is unnecessary using theopening/closing mechanism, it is possible to prevent the oil fromflowing out to the outside of the pump housing together with the bubblesvia the passage in the period in which the discharging of the bubbles isunnecessary. The period in which the discharging of the bubbles isunnecessary is, for example, a period in which the rotation frequency ofthe engine is low and the bubbles are not easily formed in the oil.

In the configuration in which the passage includes the first passageportion and the second passage portion, it is preferable that the shaftportion includes a rotary shaft which rotationally drives the rotor, therotary shaft includes an opening/closing mechanism which opens andcloses the passage, the opening/closing mechanism includes anopening/closing valve which includes a sealing wall and a communicationbore which is disposed at a position deviated in the axial direction ofthe rotary shaft with respect to the sealing wall and is capable ofmoving in the axial direction of the rotary shaft, and theopening/closing mechanism is configured to close the passage by movingto one side of the axial direction of the rotary shaft to dispose thesealing wall between the first passage portion and the second passageportion and to open the passage by moving to the other side of the axialdirection of the rotary shaft to dispose, instead of the sealing wall,the communication bore between the first passage portion and the secondpassage portion.

According to this configuration, since it is possible to open and closethe passage merely by providing the sealing wall which has a function ofblocking the passage and the communication bore which has a function ofcommunicating with the passage in a single member (the opening/closingvalve) and moving the single member (the opening/closing valve), it ispossible to easily perform the opening and closing of the passage and itis possible to simplify the configuration of the opening/closingmechanism.

In the configuration in which the opening/closing mechanism includes thesealing wall and the communication bore, it is preferable that theopening/closing mechanism is configured to move the opening/closingvalve according to an internal pressure of a discharging port and isconfigured to close the passage by disposing the sealing wall betweenthe first passage portion and the second passage portion in a case inwhich the internal pressure of the discharging port is low and to openthe passage by disposing, instead of the sealing wall, the communicationbore between the first passage portion and the second passage portion ina case in which the internal pressure of the discharging port is high.

According to this configuration, in a case in which the rotationfrequency of the engine is lowered and the internal pressure of thedischarging port is low to an extent in which the bubbles are not easilyformed in the oil, it is possible to close the passage. However, in acase in which the rotation frequency of the engine is raised and theinternal pressure of the discharging port is high to an extent in whichthe bubbles are easily formed in the oil, it is possible to open thepassage. In other words, it is possible to effectively remove thebubbles contained in the oil while suppressing the flowing out of theoil to the outside of the pump housing.

In the configuration in which the opening/closing mechanism moves anopening/closing valve according to the internal pressure of thedischarging port, it is preferable that the opening/closing mechanismincludes a pressure chamber which is provided on one side in the axialdirection of the rotary shaft of the opening/closing valve, communicateswith the discharging port via a pressure passage, and pressurizes theopening/closing valve to move the opening/closing valve, a biasingmember which is provided on the other side in the axial direction of therotary shaft of the opening/closing valve and biases the opening/closingvalve toward the pressure chamber, and a restriction portion whichrestricts movement of the opening/closing valve to the pressure chamberside, and the opening/closing mechanism is configured to close thepassage by disposing the sealing wall between the first passage portionand the second passage portion in a state in which the opening/closingvalve and the restriction portion are caused to abut against each otherby a biasing force of the biasing member in a case in which the internalpressure of the discharging port and the pressure chamber is low and toopen the passage by disposing, instead of the sealing wall, thecommunication bore between the first passage portion and the secondpassage portion in a state in which the opening/closing valve and therestriction portion are separated from each other against the biasingforce of the biasing member by the internal pressure of the pressurechamber via the opening/closing valve in a case in which the internalpressure of the discharging port and the pressure chamber is high.

According to this configuration, it is possible to configure theopening/closing mechanism from only structural and mechanicalconfiguration elements (the pressure chamber, the opening/closing valve,the biasing member, and the restriction portion) without usingelectrical configuration elements. Therefore, since it is not necessaryto provide a configuration for supplying electrical power or the like tothe opening/closing mechanism, it is possible to simplify theconfiguration of the opening/closing mechanism.

In the oil pump according to the aspect, it is preferable that the rotoris an inscribed gear rotor which includes an outer rotor including aplurality of internal teeth and an inner rotor including a plurality ofexternal teeth which mesh with the internal teeth of the outer rotor, orthe rotor is a vane rotor which includes a rotor main body and aplurality of vanes which are provided to protrude outward from the rotormain body and form the pump chamber.

According to this configuration, in a case in which the inscribed gearrotor (the inscribed gear pump) is used, it is possible to configure theoil pump such that it is possible to obtain a great output using acomparatively small structure. In a case in which the vane rotor (thevane pump) is used, it is possible to configure the oil pump using asimple shape in which foreign matter and the like do not easily getstuck.

In the oil pump according to the aspect, it is preferable that the shaftportion includes a rotary shaft which includes a recessed portion havinga circular cross-section that is orthogonal to an axial direction of theshaft portion and extending in the axial direction and which rotatestogether with the rotor, and a fixed shaft which includes a first memberwhich is fixed to the pump housing and a second member which is insertedinto the recessed portion and is connected to the first member in astate of being capable of moving in a direction orthogonal to the axialdirection.

According to this configuration, since it is possible to allow themovement of the fixed shaft (the second member) in a directionorthogonal to the axial directions relative to the rotary shaft, it ispossible to more uniformly maintain the clearance between the fixedshaft (the second member) and the recessed portion in thecircumferential direction of the fixed shaft (the second member) ascompared to a case in which the entirety of the fixed shaft iscompletely fixed to the pump housing. Accordingly, it is possible tosuppress the clearance between the fixed shaft and the recessed portionin the circumferential direction of the fixed shaft becoming too greatand the sealing properties being inhibited. It is possible to suppressthe clearance between the fixed shaft and the recessed portion becomingtoo small and the rotation of the rotary shaft being prevented by thefixed shaft. In a case in which the entirety of the fixed shaft iscompletely fixed to the pump housing, it is necessary to consider,during the manufacturing, the tolerance between the rotary shaft and thefixed shaft and the tolerance between the fixed shaft and theconfigurations (the flange and the like) for attaching the fixed shaftto the pump housing. However, in the configuration of the fourthembodiment, it is sufficient to only consider the tolerance between therotary shaft and the first member during the manufacturing. In otherwords, it is possible to easily maintain a uniform clearance between thefixed shaft (the second member) and the recessed portion.

In this case, it is preferable that the fixed shaft includes aturn-stopping portion which connects the first member and the secondmember to each other in a state in which the second member is capable ofmoving in the direction orthogonal to the axial direction relative tothe first member.

According to this configuration, it is possible to easily realize aconfiguration which connects the second member and the first member toeach other in a state in which the movement of the fixed shaft (thesecond member) in the direction orthogonal to the axial directionrelative to the rotary shaft using the turn-stopping portion.

In the oil pump according to the aspect, it is preferable that thepassage includes a first passage portion which is provided to straddleat least one of the pump housing and the inner rotor and the shaftportion and extending in a direction intersecting an axial direction ofthe shaft portion, and a second passage portion which is provided in theshaft portion and extends in the axial direction, the shaft portionincludes a rotary shaft which includes a recessed portion having acircular cross-section that is orthogonal to the axial direction of theshaft portion and extends in the axial direction and which rotatestogether with the inner rotor, and a fixed shaft which includes a firstmember which is fixed to the pump housing and a second member which isinserted into the recessed portion and is connected to the first memberin a state of being capable of moving in a direction orthogonal to theaxial direction, and the first passage portion includes an outer passageportion which is provided to straddle the rotary shaft and the innerrotor and an inner passage portion which is provided in the fixed shaftand communicates with the outer passage portion at a predeterminedrotational position of the rotary shaft.

According to this configuration, it is possible to communicate the outerpassage portion and the inner passage portion with each other at apredetermined rotational position of the rotary shaft. Accordingly, itis possible to effectively discharge the bubbles to the outside of thepump housing using a higher pressure when the outer passage portion andthe inner passage portion communicate with each other in a case in whichthe inner passage portion faces the discharging port side more than thesuction port side.

In the oil pump according to the aspect, it is preferable that a toothbottom of the inner rotor is provided with a bubble introduction portionwhich is disposed between the pump chamber and the passage, whichcollects the bubbles inside the pump chamber and introduces thecollected bubbles into the passage.

According to this configuration, since it is possible to introduce moreof the bubbles into the passage than the oil by collecting the bubblesat the bubble introduction portion, it is possible to suppress thedischarging of the oil from the passage portion.

In the oil pump according to the aspect, it is preferable that thepassage includes a first passage portion which is provided to straddleat least one of the pump housing and the inner rotor and the shaftportion and extends in a direction intersecting the axial direction ofthe shaft portion, and a second passage portion which is provided in theshaft portion and extends in the axial direction, and one end of thefirst passage portion is connected to a tooth bottom of the inner rotor.

According to this configuration, since it is possible to dispose one endof the first passage portion at a closer position to the shaft portionat which the bubbles collect easily due to the oil being moved to theoutside of the shaft portion in the radial direction by a centrifugalforce, it is possible to more efficiently remove the bubbles.

In the oil pump according to the aspect, it is preferable that thepassage is provided to straddle the pump housing and the shaft portionand the passage on the pump housing side is formed in a groove shapewhich communicates the pump chamber and the passage on the shaft portionside with each other.

According to this configuration, since it is possible to move thebubbles from the pump chamber to the shaft portion side via the pumphousing which is a configuration which does not rotate, it is possibleto stably move the bubbles to the shaft portion side using thegroove-shaped passage as compared to a case in which the passage isprovided in the inner rotor which rotates. As a result, it is possibleto stably discharge the bubbles to the outside of the pump housing.

The principles, preferred embodiment and mode of operation of thepresent invention have been described in the foregoing specification.However, the invention which is intended to be protected is not to beconstrued as limited to the particular embodiments disclosed. Further,the embodiments described herein are to be regarded as illustrativerather than restrictive. Variations and changes may be made by others,and equivalents employed, without departing from the spirit of thepresent invention. Accordingly, it is expressly intended that all suchvariations, changes and equivalents which fall within the spirit andscope of the present invention as defined in the claims, be embracedthereby.

What is claimed is:
 1. An oil pump comprising: a pump housing having arotor accommodation space in an inner portion of the pump housing; arotor accommodated in the rotor accommodation space; a shaft portiondisposed inside the rotor; and a passage which is provided to straddleat least one of the pump housing and the rotor and the shaft portion andwhich communicates a pump chamber which is formed by the rotor insidethe pump housing with an outside of the pump housing.
 2. The oil pumpaccording to claim 1, wherein the passage includes a first passageportion which is provided to straddle at least one of the pump housingand the rotor and the shaft portion and extends in a directionintersecting an axial direction of the shaft portion, and a secondpassage portion which is provided in the shaft portion and extends inthe axial direction.
 3. The oil pump according to claim 1, wherein theshaft portion includes an opening/closing mechanism which opens andcloses the passage.
 4. The oil pump according to claim 2, wherein theshaft portion includes a rotary shaft which rotationally drives therotor, the rotary shaft includes an opening/closing mechanism whichopens and closes the passage, the opening/closing mechanism includes anopening/closing valve which includes a sealing wall and a communicationbore which is disposed at a position deviated in the axial direction ofthe rotary shaft with respect to the sealing wall and is capable ofmoving in the axial direction of the rotary shaft, and theopening/closing mechanism is configured to close the passage by movingto one side of the axial direction of the rotary shaft to dispose thesealing wall between the first passage portion and the second passageportion and to open the passage by moving to the other side of the axialdirection of the rotary shaft to dispose, instead of the sealing wall,the communication bore between the first passage portion and the secondpassage portion.
 5. The oil pump according to claim 4, wherein theopening/closing mechanism is configured to move the opening/closingvalve according to an internal pressure of a discharging port and isconfigured to close the passage by disposing the sealing wall betweenthe first passage portion and the second passage portion in a case inwhich the internal pressure of the discharging port is low and to openthe passage by disposing, instead of the sealing wall, the communicationbore between the first passage portion and the second passage portion ina case in which the internal pressure of the discharging port is high.6. The oil pump according to claim 5, wherein the opening/closingmechanism includes a pressure chamber which is provided on one side inthe axial direction of the rotary shaft of the opening/closing valve,communicates with the discharging port via a pressure passage, andpressurizes the opening/closing valve to move the opening/closing valve,a biasing member which is provided on the other side in the axialdirection of the rotary shaft of the opening/closing valve and biasesthe opening/closing valve toward the pressure chamber, and a restrictionportion which restricts movement of the opening/closing valve to thepressure chamber side, and the opening/closing mechanism is configuredto close the passage by disposing the sealing wall between the firstpassage portion and the second passage portion in a state in which theopening/closing valve and the restriction portion are caused to abutagainst each other by a biasing force of the biasing member in a case inwhich the internal pressure of the discharging port and the pressurechamber is low and to open the passage by disposing, instead of thesealing wall, the communication bore between the first passage portionand the second passage portion in a state in which the opening/closingvalve and the restriction portion are separated from each other againstthe biasing force of the biasing member by the internal pressure of thepressure chamber via the opening/closing valve in a case in which theinternal pressure of the discharging port and the pressure chamber ishigh.
 7. The oil pump according to claim 1, wherein the rotor is aninscribed gear rotor which includes an outer rotor including a pluralityof internal teeth and an inner rotor including a plurality of externalteeth which mesh with the internal teeth of the outer rotor, or therotor is a vane rotor which includes a rotor main body and a pluralityof vanes which are provided to protrude outward from the rotor main bodyand form the pump chamber.
 8. The oil pump according to claim 1, whereinthe shaft portion includes a rotary shaft which includes a recessedportion having a circular cross-section that is orthogonal to an axialdirection of the shaft portion and extending in the axial direction andwhich rotates together with the rotor, and a fixed shaft which includesa first member which is fixed to the pump housing and a second memberwhich is inserted into the recessed portion and is connected to thefirst member in a state of being capable of moving in a directionorthogonal to the axial direction.
 9. The oil pump according to claim 8,wherein the fixed shaft includes a turn-stopping portion which connectsthe first member and the second member to each other in a state in whichthe second member is capable of moving in the direction orthogonal tothe axial direction relative to the first member.
 10. The oil pumpaccording to claim 7, wherein the passage includes a first passageportion which is provided to straddle at least one of the pump housingand the inner rotor and the shaft portion and extending in a directionintersecting an axial direction of the shaft portion, and a secondpassage portion which is provided in the shaft portion and extends inthe axial direction, the shaft portion includes a rotary shaft whichincludes a recessed portion having a circular cross-section that isorthogonal to the axial direction of the shaft portion and extends inthe axial direction and which rotates together with the inner rotor, anda fixed shaft which includes a first member which is fixed to the pumphousing and a second member which is inserted into the recessed portionand is connected to the first member in a state of being capable ofmoving in a direction orthogonal to the axial direction, and the firstpassage portion includes an outer passage portion which is provided tostraddle the rotary shaft and the inner rotor and an inner passageportion which is provided in the fixed shaft and communicates with theouter passage portion at a predetermined rotational position of therotary shaft.
 11. The oil pump according to claim 7, wherein a toothbottom of the inner rotor is provided with a bubble introduction portionwhich is disposed between the pump chamber and the passage, collects thebubbles inside the pump chamber and introduces the collected bubblesinto the passage.
 12. The oil pump according to claim 7, wherein thepassage includes a first passage portion which is provided to straddleat least one of the pump housing and the inner rotor and the shaftportion and extends in a direction intersecting the axial direction ofthe shaft portion, and a second passage portion which is provided in theshaft portion and extends in the axial direction, and one end of thefirst passage portion is connected to a tooth bottom of the inner rotor.13. The oil pump according to claim 2, wherein the passage is providedto straddle the pump housing and the shaft portion and the passage onthe pump housing side is formed in a groove shape which communicates thepump chamber and the passage on the shaft portion side with each other.